SULFIDE OXIDATION AND OXIDATIVE HYDROLYSIS OF THIOESTERS BY PEROXYMONOSULFATE ION

Peroxymonosulfate ion, HSO5-, as OXONE, in aqueous MeCN readily converts aryl thiobenzoates, XC(6)H(4)CO.SC(6)H(4)Z (X = p-OMe, p-Me, H, p-Cl, p-CN; Z = p-OMe, p-Me, H, m-OMe, p-Cl, m-Cl, p-NO2) into carboxylic and sulfonic acids. Reactions are second order and have small substituent effects, with rho approximate to -0.6 based on sigma(m) and sigma(p) substituent parameters, but rates increase markedly with increasing water content in aqueous MeCN and entropies of activation are negative. The initial step is very similar to the oxidation of methyl aryl sulfides by HSO5- which has similar solvent and substituent effects. Enthalpies of activation are much lower for oxidation of the sulfides than of the corresponding esters but entropies of activation are similar.